EP0095770A1 - Gas-Laser-Vorrichtung - Google Patents

Gas-Laser-Vorrichtung Download PDF

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Publication number
EP0095770A1
EP0095770A1 EP83105336A EP83105336A EP0095770A1 EP 0095770 A1 EP0095770 A1 EP 0095770A1 EP 83105336 A EP83105336 A EP 83105336A EP 83105336 A EP83105336 A EP 83105336A EP 0095770 A1 EP0095770 A1 EP 0095770A1
Authority
EP
European Patent Office
Prior art keywords
cathode
power source
oscillation mode
members
shaped
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP83105336A
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English (en)
French (fr)
Other versions
EP0095770B1 (de
Inventor
Yukio Kawakubo
Hiroyuki Sugawara
Kouji Kuwabara
Toshiharu Shirakura
Satoshi Takemori
Kouji Sasaki
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hitachi Ltd
Original Assignee
Hitachi Ltd
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Filing date
Publication date
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
Publication of EP0095770A1 publication Critical patent/EP0095770A1/de
Application granted granted Critical
Publication of EP0095770B1 publication Critical patent/EP0095770B1/de
Expired legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/09—Processes or apparatus for excitation, e.g. pumping
    • H01S3/097—Processes or apparatus for excitation, e.g. pumping by gas discharge of a gas laser
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/02—Constructional details
    • H01S3/03—Constructional details of gas laser discharge tubes
    • H01S3/038—Electrodes, e.g. special shape, configuration or composition
    • H01S3/0385—Shape
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
    • H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
    • H01S3/02—Constructional details
    • H01S3/03—Constructional details of gas laser discharge tubes
    • H01S3/038—Electrodes, e.g. special shape, configuration or composition
    • H01S3/0384—Auxiliary electrodes, e.g. for pre-ionisation or triggering, or particular adaptations therefor

Definitions

  • a current threshold I th below which the oscillation does not occur. It is important from an application aspect to note that, in the pulsed oscillation mode, a small current I o in the predischarge state is set below the threshold Ith.
  • the glow discharge is effected at the small current I with the cathode having a discharge effective surface set to an optimum value for continuous high output, only a portion of the cathode surface contributes to the discharge. This can be readily confirmed by the fact that the high intensity light in front of the cathode called the negative glow appeares in an arc partially along the cathode surface, when a ring cathode is used.
  • a plurality of cathode members each having a predetermined discharge effective cathode surface and each being electrically isolated from others are arranged opposite to an anode, and switching means selects cathode member(s) used for a continuous wave oscillation mode and cathode member(s) used for a pulsed oscillation mode.
  • the total area of the discharge effective cathode surface(s) of the cathode member(s) used for the pulsed oscillation mode is selected to be smaller than that of the discharge effective cathode surface(s) of the cathode member(s) used for the continuous wave oscillation mode.
  • the single device can be operated in both the continuous wave oscillation mode and the pulsed oscillation mode.
  • the gas laser device has a cylindrical anode 3, a disc-shaped cathode member 4 for a continuous wave oscillation mode (hereinafter referred to as a first cathode) and a disc-shaped cathode member 5 (hereinafter referred to as a second cathode) for a pulsed oscillation mode arranged in a discharge tube 2 having a reflection mirror (total reflection mirror) 2A and a reflection mirror (output mirror) 2B at opposite ends.
  • the thickness t l of the first cathode 4 is larger than that t 2 of the second cathode 5.
  • the structures of the cathodes 4 and 5 are identical except the thickness.
  • the first cathode 4 has an inner aperture 6, and a discharge effective cathode surface 8 is formed on an inner periphery facing the aperture 6.
  • a plurality of gas flow paths 10 through which a gas medium 2C (see Fig. 1) flows are formed across the cathode surface 8 and an outer periphery 9.
  • the gas medium 2C is circulated by a forced circulation system (not shown) which communicates with the discharge tube 2.
  • An insulated tube having one end thereof connected to a tube wall between the reflection mirror 2A of the discharge tube 2 and the second cathode 5 and the other end thereof connected to a tube wall between the anode 3 of the discharge tube 2 and the output mirror 2B is provided so that gas flow paths are formed together with the discharge tube 2.
  • the insulated tube contains therein a blower for flowing the gas medium 2C in the discharge tube 2 from the cathode to the anode, and a heat exchanger for cooling the gas medium is arranged on a portion of the insulated tube near the anode 3.
  • a high voltage source 15 is connected across the anode 3 and the first cathode 4 and the second cathode 5.
  • the cathode structure having the gas flow paths 10 shown in Figs. 2 and 3 is disclosed in the Japanese Patent Application Laid-Open No. 55-30817 laid-open on March 4, 1980.
  • the cathode surface other than the cathode surface 8 facing the aperture 6 is coated with an insulative coating.
  • the glow discharge formed between the anode and the cathode is urged to the wall surface of the discharge tube 2 by the flow of the gas medium which is circulated at a high speed and a space having no glow is formed upstream of the discharge tube 2 close to the cathode.
  • the gas flow paths 10 are provided to prevent such an inconvenience.
  • the high voltage source 15 comprises a first power source 16 for the continuous wave oscillation and a second power source for the pulsed oscillation.
  • a first stabilizing resistor 19 and a first switch 18 are connected between the first power source 16 and the first cathode 4.
  • the second power source 17 comprises a high D.C. voltage source 17A and a pulse voltage source 17B.
  • the pulse voltage source 17B is connected to the anode 3 and a ground 20, and a second stabilizing resistor 21 and a second switch 22 are connected between the high D.C. power source 17A and the second cathode 5.
  • a third switch 23 is inserted between the first power source 16 and the second power source 17.
  • the second switch 22 When the gas laser device is to be operated in the continuous wave oscillation mode, the second switch 22 is opened and the first and third switches 18 and 23 are closed to connect the first power source 16 between the anode 3 and the first and second cathodes 4 and 5.
  • the voltage is applied between the anode 3 and the first and second cathodes 4 and 5 so that a glow discharge occurs between the anode 3 and the cathode surfaces 8 of the first and second cathodes.
  • the discharge area (a sum of the cathode surface area of the first cathode 4 and the cathode surface area of the second cathode 5) is represented by 5 1 as shown in Fig. 4B.
  • the laser beam is reciprocally and repeatedly reflected between the reflection mirror 2A and the output mirror 2B in the laser medium 2C excited by the glow discharge, and a portion 30 of the laser beam is continuously outputted through the output mirror 2B. If only a small continuous output is required, only one of the first and second cathodes 4 and 5 may be used.
  • the second switch 22 of Fig. 1 is closed and the first and third switches 18 and 23 are opened to connect only the second cathode 5 to the second power source 17.
  • the discharge area (the cathode surface area of the second cathode 5) S 2 in the pulsed oscillation mode is selected to an area suitable to the pulsed oscillation which is smaller than the discharge area S 1 in the continuous wave oscillation mode. More particularly, the discharge area S 2 is determined in the following manner.
  • the output pulse width of the pulse laser required in the laser application is smaller than 1 ms. In order to attain such a fast response of the glow discharge, some predischarge is needed.
  • the predischarge is effected by the glow discharge at a low current I by the high D.C. voltage source 17A. Since a current density on the cathode surface when the glow discharge spreads over the entire cathode surface is constant for a given gas pressure, the negative glow spreads over the entire cathode surface even with a predischarge current lower than an oscillation threshold if the discharge area S2 in the pulsed oscillation mode is sufficiently smaller than the discharge area S in the continuous wave oscillation mode. Accordingly, as shown in Fig. 4C, a stable high power pulse laser beam is produced.
  • the discharge area S 2 may be selected to 1/3 to 1/2 of the discharge area S 1 in the high power continuous wave oscillation mode.
  • the desired areas S 1 and S 2 can be readily obtained by adjusting the thickness t l of the first. cathode 4 and the thickness t 2 of the second electrode 5 such that they meet a relation of t 1 > t 2 .
  • the inner diameter of the first cahode 4 closer to the anode 3 is slightly larger than the inner diameter of the second cathode 5 in order that the cathode 4 at the downstream side of the gas flow is prevented from being thermally damaged by a glow discharge from the cathode 5 at the upstream of the gas flow.
  • the thickness t 2 may be practically selected to 1/3 to 1/2 of the thickness t l .
  • numeral 25 denotes a trigger electrode for facilitating the discharge, and a resistor 26 is connected between the trigger electrode 25 and the ground.
  • a single gas laser device can produce a high continuous power output and a high pulse power output by merely switching the switching means 24 including the switches 18, 22 and 23.
  • a pulse peak output of as high as 13 kW was produced with an axial flow type (coaxial type) C0 2 gas laser device which produces a continuous output of 2.5 kW.
  • the first, second and third switches are arranged between the first and second power sources and the first and second stabilizing resistors, but it is apparent that the same effect is attained when a portion thereof is arranged between the first and second stabilizing resistors and the first and second cathodes.
  • the both cathodes may be of the same thickness.
  • the cathode thickness is selected to the thickness t 2 of the pulsed oscillation cathode 5 of Fig. 1.
  • the respective cathode members are connected to switching neans comprising switches 18', 22' and 23' through a stabilizing resistor 41.
  • the switch 22' is opened and the switches 18' and 23' are closed so that all the cathode members 50A - 50F are connected to the continuous wave oscillation power source 16 and the glow discharge occurs on the cathode surfaces 8'.
  • the switches 18' and 23' are opened and the switch 22' is closed so that the cathode members 50A, 50C and 50E are connected to the pulsed oscillation power source 17 and the glow discharge occurs on the cathode surfaces 8'.
  • the single cathode 50 can be used either for the continuous wave oscillation and for the pulsed oscillation.
  • the cathode members shown in Figs. 2 and 5 have the gas flow paths 10 or 10', but the advantage of the present invention is equally attained with the disc-shaped or sector-shaped cathode members having no gas flow path.
  • the axial flow type (coaxial type) laser device having the disc-shaped or sector-shaped cathode was explained, but the present invention can also be applied to a cathode of other shape, to a three-axis orthogonal type device in which a gas flow direction, a discharge direction and a laser beam axis are orthogonal to each other, and to a two-axis orthogonal type device in which one of them is orthogonal to the other two directions.
  • Fig. 6 shows major portions of a further embodiment of the present invention. Ends, which form discharge effective cathode surfaces, of a plurality of pin-shaped cathode members 60A - 60F of the same dimension supported on an appropriate insulating member 61 are arranged to face a plate-like anode 63.
  • the cathode members 60A - 60F are connected to the power sources 16 and 17 through the switching means 24' in the same manner as the embodiment of Fig. 5.
  • Fig. 7 shows major portions of a still further embodiment of the present invention.
  • Respective first sides, which form the discharge effective cathode surfaces, of a plurality of L-shaped cathode members 70A - 70F of the same dimension supported on an appropriate insulating member (not shown) are arranged to face a plate-like anode 73.
  • the cathode members 70A - 70F are connected to the power sources 16 and 17 through the switching means 24' in the same manner as the embodiment of Fig. 5.
  • cathode members While six cathode members are shown in each of Figs. 5, 6 and 7, the number of the cathode members may be any number larger than one.
  • Fig. 8 shows major portions of a furthermore embodiment of the present invention.
  • Two U-shaped wire cathode members 84 and 85 are arranged to face a plate-like anode 83.
  • the diameter of the cathode member 84 is larger than the diameter of the cathode member 85.
  • the cathode members 84 and 85 are connected to the power sources 16 and 17 through the switching means 24 in the same manner as the cathode members 4 and 5 of Fig. 1.
  • Arrows 67, 77 and 87 shown in Figs. 6, 7 and 8, respectively, show the directions of the gas flow.
  • the cathode member 64 downstream of the gas flow is positioned higher than the upstream cathode member 85 in order that the downstream cathode member 84 is prevented from being thermally damaged by a glow discharge from the upstream cathode member 85.
  • the arrangements shown in Figs. 6, 7 and 8 can also be applied to the two-axis orthogonal type device and the three-axis orthogonal type device.
  • the plurality of cathode members are arranged to face the anode and the total area of the discharge effective cathode surface(s) of the cathode member(s) used for the pulsed oscillation is selected to be smaller than that of the discharge effective cathode surface(s) of the cathode member(s) used for the continuous wave oscillation.
  • the single gas laser device can produce the high continuous power output and the high pulse power output. Accordingly, a gas laser device having a wide application for heating can be provided.

Landscapes

  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Optics & Photonics (AREA)
  • Lasers (AREA)
EP83105336A 1982-06-02 1983-05-30 Gas-Laser-Vorrichtung Expired EP0095770B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP93211/82 1982-06-02
JP57093211A JPS58212189A (ja) 1982-06-02 1982-06-02 ガスレ−ザ発生装置

Publications (2)

Publication Number Publication Date
EP0095770A1 true EP0095770A1 (de) 1983-12-07
EP0095770B1 EP0095770B1 (de) 1986-04-16

Family

ID=14076229

Family Applications (1)

Application Number Title Priority Date Filing Date
EP83105336A Expired EP0095770B1 (de) 1982-06-02 1983-05-30 Gas-Laser-Vorrichtung

Country Status (4)

Country Link
US (1) US4590599A (de)
EP (1) EP0095770B1 (de)
JP (1) JPS58212189A (de)
DE (1) DE3363034D1 (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2212322A (en) * 1987-11-13 1989-07-19 Ferranti Plc Gas discharge laser apparatus
CN111585152A (zh) * 2020-04-08 2020-08-25 中国科学院微电子研究所 用于激光器腔室的电极、激光器系统及曝光设备

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6114776A (ja) * 1984-06-29 1986-01-22 Matsushita Electric Ind Co Ltd ガスレ−ザ発生器
JPS6195588A (ja) * 1984-10-17 1986-05-14 Matsushita Electric Ind Co Ltd ガスレ−ザ発振器
US4710942A (en) * 1986-02-27 1987-12-01 Spectra-Physics, Inc. Variable power gas laser tube
EP0317722A3 (de) * 1987-09-28 1989-07-12 Siemens Aktiengesellschaft Gaslaser-Anordnung mit einer Entladungsröhre
KR910001160B1 (ko) * 1988-07-13 1991-02-25 한국표준 연구소 보조전극을 사용하여 기체방전 레이저의 출력을 안정화시키는 방법
US10375901B2 (en) 2014-12-09 2019-08-13 Mtd Products Inc Blower/vacuum

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3777279A (en) * 1972-03-30 1973-12-04 United Aircraft Corp Deposition of power in a moving gas stream by electric discharge means
DE2523153A1 (de) * 1975-05-24 1976-12-09 Eltro Gmbh Elektrodensystem
WO1980000514A1 (en) * 1978-08-25 1980-03-20 Hitachi Ltd Gas laser generating device

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4166986A (en) * 1977-06-10 1979-09-04 Westinghouse Electric Corp. Ballast technique for laser cathode pins
US4255720A (en) * 1978-10-02 1981-03-10 Xerox Corporation Variable diameter segmented hollow cathode laser device
US4342115A (en) * 1980-10-06 1982-07-27 United Technologies Corporation Laser discharge electrode configuration
JPS57188892A (en) * 1981-05-18 1982-11-19 Matsushita Electric Ind Co Ltd Coaxial carbon dioxide laser oscillator

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3777279A (en) * 1972-03-30 1973-12-04 United Aircraft Corp Deposition of power in a moving gas stream by electric discharge means
DE2523153A1 (de) * 1975-05-24 1976-12-09 Eltro Gmbh Elektrodensystem
WO1980000514A1 (en) * 1978-08-25 1980-03-20 Hitachi Ltd Gas laser generating device

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
APPLIED PHYSICS LETTERS, vol. 40, no. 5, March 1982, pages 359-361, American Institute of Physics, New York, USA *
PATENTS ABSTRACTS OF JAPAN, vol. 5, no. 99, (E-63)[771], 26th June 1981 & JP - A - 56 42392 (HITACHI SEISAKUSHO K.K.) 20-04-1981 *
PATENTS ABSTRACTS OF JAPAN, vol. 6, no. 16, (E-92)[894], 29th January 1982 & JP - A - 56 137 689 (MITSUBISHI DENKI K.K.) 27-10-1981 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2212322A (en) * 1987-11-13 1989-07-19 Ferranti Plc Gas discharge laser apparatus
CN111585152A (zh) * 2020-04-08 2020-08-25 中国科学院微电子研究所 用于激光器腔室的电极、激光器系统及曝光设备
CN111585152B (zh) * 2020-04-08 2022-02-08 中国科学院微电子研究所 用于激光器腔室的电极、激光器系统及曝光设备

Also Published As

Publication number Publication date
DE3363034D1 (en) 1986-05-22
US4590599A (en) 1986-05-20
JPS58212189A (ja) 1983-12-09
JPH0373151B2 (de) 1991-11-20
EP0095770B1 (de) 1986-04-16

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